How Is Energy Consumed in Smartphone Display Applications? Xiang Chen, Yiran Chen Zhan Ma, Felix C

How is Energy Consumed in Smartphone Display Applications? Xiang Chen, Yiran Chen Zhan Ma, Felix C. A. Fernandes ECE Department, University of Pittsburgh Samsung Telecommunication America Pittsburgh, PA, USA 15261 Richardson, TX, USA 75082 +1 (412) 624-5836 +1(972)761-7134 {xic33, yic52}@pitt.edu {zhan.ma, ffernandes}@sta.samsung.com ABSTRACT of these applications depends heavily on the type of display Smartphones have emerged as a popular and frequently used technology being used, which also plays an important role in platform for the consumption of multimedia. New display human-machine interaction. Many researches have already studied technologies, such as AMOLED, have been recently introduced to the power and performance of different display technologies [1]. smartphones to fulfill the requirements of these multimedia Very recently, AMOLED (Active-Matrix Organic Light Emitting applications. However, as an AMOLED screen’s power Diode) display panels have begun to replace conventional LCD consumption is determined by the display content, such (Liquid Crystal Display) technology in mainstream smartphones. applications are often limited by the battery life of the device they Compared to LCD, AMOLED offers much better display quality are running on, inspiring many researches to develop new power and higher power efficiency because of its unique lighting management schemes. In this work, we evaluate the power mechanism. This unique property has led to much research consumption of several applications on a series of Samsung involving the power evaluation and modeling of AMOLED as well smartphones and take a deep look into AMOLED's power as the performance variance among different AMOLED panel consumption and its relative contributions for multimedia apps. We designs. However, due to the large variety of AMOLED panel improve AMOLED power analysis by considering the dynamic designs and the fast pace of smartphone software development, factors in displaying, and analyze the individual factors affecting most of this research only aims at a particular smartphone device power consumption when streaming video, playing a video game, or application. It is not clear whether there is any significant power and recording video via a device’s built-in camera. Our detailed efficiency improvement between different generations of measurements refine the power analysis of smartphones and reveal AMOLED display technology or if it is possible to obtain an some interesting perspectives regarding the power consumption of overview display power efficiency under different applications. AMOLED displays in multimedia applications. In this work, we evaluate the power consumption of the displays of Categories and Subject Descriptors several high-end Samsung smartphone models. In addition to this, we discuss the power modeling of different generations of K.6.2 [Management OF Computing and Information Systems]: AMOLED screens and conduct a detailed power analysis of several Installation Management – Performance and usage measurement. popular multimedia applications. Based on the data that was General Terms collected, we draw some interesting conclusions which may Algorithms, Management, Measurement, Performance, Design. influence future research in the field. For example: • Subsequent generations of AMOLED products do not yield the Keywords significant per-unit improvement in power efficiency that was OLED display, Smartphone, AMOLED, Video power. expected. The power difference between AMOLED products is 1. INTRODUCTION mainly realized by design metrics like size and sub-pixel. Smartphones now play a large role in almost every aspect of our •The power consumption of chromatic color can be efficiently daily lives, being utilized in activities such as communication, reduced by implementing a dynamic color tuning technique. personal planning, and entertainment. Although the complexity and • The power consumed during the video decoding process is capabilities of these devices continues to grow at an amazing pace, responsible for only a small portion of the total power required for smartphones are now expected to continually become lighter and the end user to actually view the video. slimmer. When combined with power-hungry multimedia applications, the limited battery capacity allowed by these •In video games, the AMOLED display’s power consumption expectations now motivates significant investment into smartphone varies greatly, and it is relatively small in some cases when power management research. compared to the overall system power consumption. Multimedia applications, such as streaming video players, games, •The power consumed by the AMOLED during video recording is and image and video capturing tools, now comprise a considerable relatively small compared to the overall power consumption. portion of the daily usage of smartphones. The power consumption The remainder of our paper is organized as follows: Section 2 Permission to make digital or hard copies of all or part of this work for presents previous related work; Section 3 gives our adopted personal or classroom use is granted without fee provided that copies are methodology for power evaluation, including the devices under test not made or distributed for profit or commercial advantage and that copies (DUTs) and the test environment setup; Section 4 models the power bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific consumptions of several different AMOLED panels on Samsung permission and/or a fee. smartphones; Section 5 presents the power analysis’ of video ACM HotMobile'13, February 26-27, 2013, Jekyll Island, Georgia, USA. streaming players, video games, and camera recording, Copyright 2013 ACM 978-1-4503-1421-3 ...$10.00. respectively; Section 6 concludes our work. 2. RELATED WORK Panel Smartphone Resolution Since its development, AMOLED technology has been the topic of Size a great deal of research, much of which has attempted to describe Nexus S 4.0” 480*800 and model its power characteristics. The authors of [2] presented a Galaxy S2 4.5” 480*800 classic AMOLED power modeling in smartphone, which is Galaxy 4.65” 720*1280 adopted in this paper. The authors of [3] evaluated the AMOLED Nexus power model’s accuracy in practical performance and helped Galaxy S3 4.8” 720*1280 application developers to improve the energy efficiency of their smartphone applications. OLED power model is part of the system (a) (b) power model. The display modeling of AMOLED has also been Fig. 1. (a) AMOLED sub-pixel matrix; (b) Smartphone integrated into a system level power monitor and analyzer, as done AMOLED screen specs. in [8] and [9]. contrast experiments. Power optimization schemes based on AMOLED displays have We adopted a mobile device power monitor produced by Monsoon also been studied from the applications point of view. The authors Inc. for real time power measurement. It supports a sampling of [15] reduced the power consumed while displaying an arbitrary frequency up to 5 kHz and can be used to replace the battery as the image through the use of OLED’s dynamic voltage scaling (DVS) power supply to the smartphone. The power monitor is directly technology, while the authors of [4] extended this DVS scheme into connected to the smartphone and records a power histogram. video streams. The authors of [7] extended the dynamic gamma During the power evaluation of the display modules, we disabled correction power saving scheme for video games to the AMOLED all unnecessary system services that may have caused any platform. The author of [5] shows OLED screens contribute significant power consumption noise, including 4G and Wi-Fi significantly to the energy consumption of web browser and then network communication, background services, and power applies the optimization techniques from [6] to reduce it. These optimization applications. The contrast experiments are designed to works pointed out that, while a smartphone spends most time idle separate the power consumption of display from that of the system, when web browsing, streaming video, playing video game, and e.g., CPU and GPU. Most power consumption test are completed camera recording, the smartphone demands significant system while the device’s screen brightness is set to maximum. The resources in a continuous manner. However, we find the power specific test bench details will be presented in later sections. contribution made by the OLED screen can be small. 4. AMOLED DISPLAY EXPLORATION 3. METHODOLOGY 3.1 Devices Under Test (DUTs) 4.1 AMOLED Power Evaluation on Sub-pixel Different from previous research, instead of directly measuring and We examined five Samsung products, including the Nexus S then comparing the power consumption of each entire screen, we (released in 2010), the Galaxy S1, Nexus, and S2 (released in attempt to normalize the displays and compare the per-unit power 2011), and the Galaxy S3 (released in 2012). During the tests, the efficiency for different AMOLED products. Because of this we devices ran the Android operating system and a suite of test found that, in contrast to the conclusions drawn by previous applications. The screens of all the tested devices are all based on research, when comparing the power efficiency between different AMOLED technology, though they are built with different display generations of AMOLED technology: sizes, resolutions, and technology generations, i.e., Super AMOLED, Super AMOLED Plus and Super

Load more